"If an arduous and dangerous journey where you might not come back alive, but it's a glorious adventure, sounds appealing, Mars is the place. That's the ad for Mars," he said.
"Honestly, a bunch of people probably will die in the beginning. It's tough sledging over there, you know," he added.
"We don't make anyone go. It's volunteers only."
Musk spoke to Diamandis this week in Cape Canaveral, Florida, during the announcement of the $100 million Carbon Removal project.
The project is "aimed at tackling the biggest threat facing humanity - fighting climate change and rebalancing Earth's carbon cycle" and is being funded by Musk's philanthropic organisation.
"This four-year global competition invites innovators and teams from anywhere on the planet to create and demonstrate solutions that can pull carbon dioxide directly from the atmosphere or oceans, and sequester it durably and sustainably," the site for the project states.